1 files changed, 217 insertions, 34 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index b0c9349da5..1f80ac5872 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -43,6 +43,7 @@
 #include "qwindowswindow.h"
 #include "qwindowskeymapper.h"
 #include "qwindowsmousehandler.h"
+#include "qwindowspointerhandler.h"
 #include "qtwindowsglobal.h"
 #include "qwindowsmenu.h"
 #include "qwindowsmime.h"
@@ -52,7 +53,7 @@
 #endif
 #include "qwindowstheme.h"
 #include <private/qguiapplication_p.h>
-#ifndef QT_NO_ACCESSIBILITY
+#if QT_CONFIG(accessibility)
 #  include "uiautomation/qwindowsuiaaccessibility.h"
 #endif
 #if QT_CONFIG(sessionmanager)
@@ -62,20 +63,20 @@
 #include "qwindowsscreen.h"
 #include "qwindowstheme.h"
 
-#include <QtGui/qtguiglobal.h>
-#include <QtGui/QWindow>
+#include <QtGui/qwindow.h>
 #include <qpa/qwindowsysteminterface.h>
+#include <qpa/qwindowsysteminterface_p.h>
 #include <qpa/qplatformnativeinterface.h>
-#include <QtGui/QGuiApplication>
-#include <QtGui/QOpenGLContext>
-
-#include <QtCore/QSet>
-#include <QtCore/QHash>
-#include <QtCore/QStringList>
-#include <QtCore/QDebug>
-#include <QtCore/QOperatingSystemVersion>
-#include <QtCore/QSysInfo>
-#include <QtCore/QScopedArrayPointer>
+#include <QtGui/qguiapplication.h>
+#include <QtGui/qopenglcontext.h>
+
+#include <QtCore/qset.h>
+#include <QtCore/qhash.h>
+#include <QtCore/qstringlist.h>
+#include <QtCore/qdebug.h>
+#include <QtCore/qoperatingsystemversion.h>
+#include <QtCore/qsysinfo.h>
+#include <QtCore/qscopedpointer.h>
 #include <QtCore/private/qsystemlibrary_p.h>
 
 #include <QtEventDispatcherSupport/private/qwindowsguieventdispatcher_p.h>
@@ -85,11 +86,11 @@
 #include <windowsx.h>
 #include <comdef.h>
 #include <dbt.h>
+#include <wtsapi32.h>
 
 QT_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(lcQpaWindows, "qt.qpa.windows")
-Q_LOGGING_CATEGORY(lcQpaBackingStore, "qt.qpa.backingstore")
 Q_LOGGING_CATEGORY(lcQpaEvents, "qt.qpa.events")
 Q_LOGGING_CATEGORY(lcQpaGl, "qt.qpa.gl")
 Q_LOGGING_CATEGORY(lcQpaMime, "qt.qpa.mime")
@@ -147,7 +148,7 @@ static inline bool sessionManagerInteractionBlocked() { return false; }
 
 static inline int windowDpiAwareness(HWND hwnd)
 {
-    return QWindowsContext::user32dll.getWindowDpiAwarenessContext && QWindowsContext::user32dll.getWindowDpiAwarenessContext
+    return QWindowsContext::user32dll.getWindowDpiAwarenessContext && QWindowsContext::user32dll.getAwarenessFromDpiAwarenessContext
         ? QWindowsContext::user32dll.getAwarenessFromDpiAwarenessContext(QWindowsContext::user32dll.getWindowDpiAwarenessContext(hwnd))
         : -1;
 }
@@ -194,14 +195,35 @@ void QWindowsUser32DLL::init()
     getDisplayAutoRotationPreferences = (GetDisplayAutoRotationPreferences)library.resolve("GetDisplayAutoRotationPreferences");
     setDisplayAutoRotationPreferences = (SetDisplayAutoRotationPreferences)library.resolve("SetDisplayAutoRotationPreferences");
 
+    if (QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows8) {
+        enableMouseInPointer = (EnableMouseInPointer)library.resolve("EnableMouseInPointer");
+        getPointerType = (GetPointerType)library.resolve("GetPointerType");
+        getPointerInfo = (GetPointerInfo)library.resolve("GetPointerInfo");
+        getPointerDeviceRects = (GetPointerDeviceRects)library.resolve("GetPointerDeviceRects");
+        getPointerTouchInfo = (GetPointerTouchInfo)library.resolve("GetPointerTouchInfo");
+        getPointerFrameTouchInfo = (GetPointerFrameTouchInfo)library.resolve("GetPointerFrameTouchInfo");
+        getPointerFrameTouchInfoHistory = (GetPointerFrameTouchInfoHistory)library.resolve("GetPointerFrameTouchInfoHistory");
+        getPointerPenInfo = (GetPointerPenInfo)library.resolve("GetPointerPenInfo");
+        getPointerPenInfoHistory = (GetPointerPenInfoHistory)library.resolve("GetPointerPenInfoHistory");
+        skipPointerFrameMessages = (SkipPointerFrameMessages)library.resolve("SkipPointerFrameMessages");
+    }
+
     if (QOperatingSystemVersion::current()
         >= QOperatingSystemVersion(QOperatingSystemVersion::Windows, 10, 0, 14393)) {
         enableNonClientDpiScaling = (EnableNonClientDpiScaling)library.resolve("EnableNonClientDpiScaling");
         getWindowDpiAwarenessContext = (GetWindowDpiAwarenessContext)library.resolve("GetWindowDpiAwarenessContext");
         getAwarenessFromDpiAwarenessContext = (GetAwarenessFromDpiAwarenessContext)library.resolve("GetAwarenessFromDpiAwarenessContext");
+        systemParametersInfoForDpi = (SystemParametersInfoForDpi)library.resolve("SystemParametersInfoForDpi");
     }
 }
 
+bool QWindowsUser32DLL::supportsPointerApi()
+{
+    return enableMouseInPointer && getPointerType && getPointerInfo && getPointerDeviceRects
+            && getPointerTouchInfo && getPointerFrameTouchInfo && getPointerFrameTouchInfoHistory
+            && getPointerPenInfo && getPointerPenInfoHistory && skipPointerFrameMessages;
+}
+
 void QWindowsShcoreDLL::init()
 {
     if (QOperatingSystemVersion::current() < QOperatingSystemVersion::Windows8_1)
@@ -239,6 +261,7 @@ struct QWindowsContextPrivate {
     int m_defaultDPI = 96;
     QWindowsKeyMapper m_keyMapper;
     QWindowsMouseHandler m_mouseHandler;
+    QWindowsPointerHandler m_pointerHandler;
     QWindowsMimeConverter m_mimeConverter;
     QWindowsScreenManager m_screenManager;
     QSharedPointer<QWindowCreationContext> m_creationContext;
@@ -256,7 +279,7 @@ QWindowsContextPrivate::QWindowsContextPrivate()
     QWindowsContext::user32dll.init();
     QWindowsContext::shcoredll.init();
 
-    if (m_mouseHandler.touchDevice())
+    if (m_pointerHandler.touchDevice() || m_mouseHandler.touchDevice())
         m_systemInfo |= QWindowsContext::SI_SupportsTouch;
     m_displayContext = GetDC(0);
     m_defaultDPI = GetDeviceCaps(m_displayContext, LOGPIXELSY);
@@ -281,10 +304,6 @@ QWindowsContext::QWindowsContext() :
     const QByteArray bv = qgetenv("QT_QPA_VERBOSE");
     if (!bv.isEmpty())
         QLoggingCategory::setFilterRules(QString::fromLocal8Bit(bv));
-#if QT_CONFIG(tabletevent)
-    d->m_tabletSupport.reset(QWindowsTabletSupport::create());
-    qCDebug(lcQpaTablet) << "Tablet support: " << (d->m_tabletSupport.isNull() ? QStringLiteral("None") : d->m_tabletSupport->description());
-#endif
 }
 
 QWindowsContext::~QWindowsContext()
@@ -310,12 +329,17 @@ bool QWindowsContext::initTouch(unsigned integrationOptions)
     if (d->m_systemInfo & QWindowsContext::SI_SupportsTouch)
         return true;
 
-    QTouchDevice *touchDevice = d->m_mouseHandler.ensureTouchDevice();
+    QTouchDevice *touchDevice = (d->m_systemInfo & QWindowsContext::SI_SupportsPointer) ?
+                d->m_pointerHandler.ensureTouchDevice() : d->m_mouseHandler.ensureTouchDevice();
     if (!touchDevice)
         return false;
 
-    if (!(integrationOptions & QWindowsIntegration::DontPassOsMouseEventsSynthesizedFromTouch))
-        touchDevice->setCapabilities(touchDevice->capabilities() | QTouchDevice::MouseEmulation);
+    if (d->m_systemInfo & QWindowsContext::SI_SupportsPointer) {
+        QWindowSystemInterfacePrivate::TabletEvent::setPlatformSynthesizesMouse(false);
+    } else {
+        if (!(integrationOptions & QWindowsIntegration::DontPassOsMouseEventsSynthesizedFromTouch))
+            touchDevice->setCapabilities(touchDevice->capabilities() | QTouchDevice::MouseEmulation);
+    }
 
     QWindowSystemInterface::registerTouchDevice(touchDevice);
 
@@ -330,6 +354,33 @@ bool QWindowsContext::initTouch(unsigned integrationOptions)
     return true;
 }
 
+bool QWindowsContext::initTablet(unsigned integrationOptions)
+{
+    Q_UNUSED(integrationOptions);
+#if QT_CONFIG(tabletevent)
+    d->m_tabletSupport.reset(QWindowsTabletSupport::create());
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool QWindowsContext::initPointer(unsigned integrationOptions)
+{
+    if (integrationOptions & QWindowsIntegration::DontUseWMPointer)
+        return false;
+
+    if (QOperatingSystemVersion::current() < QOperatingSystemVersion::Windows8)
+        return false;
+
+    if (!QWindowsContext::user32dll.supportsPointerApi())
+        return false;
+
+    QWindowsContext::user32dll.enableMouseInPointer(TRUE);
+    d->m_systemInfo |= QWindowsContext::SI_SupportsPointer;
+    return true;
+}
+
 void QWindowsContext::setTabletAbsoluteRange(int a)
 {
 #if QT_CONFIG(tabletevent)
@@ -340,6 +391,11 @@ void QWindowsContext::setTabletAbsoluteRange(int a)
 #endif
 }
 
+void QWindowsContext::setDetectAltGrModifier(bool a)
+{
+    d->m_keyMapper.setDetectAltGrModifier(a);
+}
+
 int QWindowsContext::processDpiAwareness()
 {
     int result;
@@ -548,7 +604,7 @@ void QWindowsContext::unregisterWindowClasses()
 {
     const HINSTANCE appInstance = static_cast<HINSTANCE>(GetModuleHandle(0));
 
-    foreach (const QString &name,  d->m_registeredWindowClassNames) {
+    for (const QString &name : qAsConst(d->m_registeredWindowClassNames)) {
         if (!UnregisterClass(reinterpret_cast<LPCWSTR>(name.utf16()), appInstance) && QWindowsContext::verbose)
             qErrnoWarning("UnregisterClass failed for '%s'", qPrintable(name));
     }
@@ -632,12 +688,16 @@ QWindow *QWindowsContext::findWindow(HWND hwnd) const
 
 QWindow *QWindowsContext::windowUnderMouse() const
 {
-    return d->m_mouseHandler.windowUnderMouse();
+    return (d->m_systemInfo & QWindowsContext::SI_SupportsPointer) ?
+        d->m_pointerHandler.windowUnderMouse() : d->m_mouseHandler.windowUnderMouse();
 }
 
 void QWindowsContext::clearWindowUnderMouse()
 {
-    d->m_mouseHandler.clearWindowUnderMouse();
+    if (d->m_systemInfo & QWindowsContext::SI_SupportsPointer)
+        d->m_pointerHandler.clearWindowUnderMouse();
+    else
+        d->m_mouseHandler.clearWindowUnderMouse();
 }
 
 /*!
@@ -696,6 +756,37 @@ QWindowsWindow *QWindowsContext::findPlatformWindowAt(HWND parent,
     return result;
 }
 
+bool QWindowsContext::isSessionLocked()
+{
+    bool result = false;
+    const DWORD sessionId = WTSGetActiveConsoleSessionId();
+    if (sessionId != 0xFFFFFFFF) {
+        LPTSTR buffer = nullptr;
+        DWORD size = 0;
+#if !defined(Q_CC_MINGW)
+        if (WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, sessionId,
+                                       WTSSessionInfoEx, &buffer, &size) == TRUE
+            && size > 0) {
+            const WTSINFOEXW *info = reinterpret_cast<WTSINFOEXW *>(buffer);
+            result = info->Level == 1 && info->Data.WTSInfoExLevel1.SessionFlags == WTS_SESSIONSTATE_LOCK;
+            WTSFreeMemory(buffer);
+        }
+#else   // MinGW as of 7.3 does not have WTSINFOEXW in wtsapi32.h
+        // Retrieve the flags which are at offset 16 due to padding for 32/64bit alike.
+        if (WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, sessionId,
+                                       WTS_INFO_CLASS(25), &buffer, &size) == TRUE
+            && size >= 20) {
+            const DWORD *p = reinterpret_cast<DWORD *>(buffer);
+            const DWORD level = *p;
+            const DWORD sessionFlags = *(p + 4);
+            result = level == 1 && sessionFlags == 1;
+            WTSFreeMemory(buffer);
+        }
+#endif // Q_CC_MINGW
+    }
+    return result;
+}
+
 QWindowsMimeConverter &QWindowsContext::mimeConverter() const
 {
     return d->m_mimeConverter;
@@ -826,6 +917,45 @@ QByteArray QWindowsContext::comErrorString(HRESULT hr)
     return result;
 }
 
+bool QWindowsContext::systemParametersInfo(unsigned action, unsigned param, void *out,
+                                           unsigned dpi)
+{
+    const BOOL result = QWindowsContext::user32dll.systemParametersInfoForDpi != nullptr && dpi != 0
+        ? QWindowsContext::user32dll.systemParametersInfoForDpi(action, param, out, 0, dpi)
+        : SystemParametersInfo(action, param, out, 0);
+    return result == TRUE;
+}
+
+bool QWindowsContext::systemParametersInfoForScreen(unsigned action, unsigned param, void *out,
+                                                    const QPlatformScreen *screen)
+{
+    return systemParametersInfo(action, param, out, screen ? screen->logicalDpi().first : 0);
+}
+
+bool QWindowsContext::systemParametersInfoForWindow(unsigned action, unsigned param, void *out,
+                                                    const QPlatformWindow *win)
+{
+    return systemParametersInfoForScreen(action, param, out, win ? win->screen() : nullptr);
+}
+
+bool QWindowsContext::nonClientMetrics(NONCLIENTMETRICS *ncm, unsigned dpi)
+{
+    memset(ncm, 0, sizeof(NONCLIENTMETRICS));
+    ncm->cbSize = sizeof(NONCLIENTMETRICS);
+    return systemParametersInfo(SPI_GETNONCLIENTMETRICS, ncm->cbSize, ncm, dpi);
+}
+
+bool QWindowsContext::nonClientMetricsForScreen(NONCLIENTMETRICS *ncm,
+                                                const QPlatformScreen *screen)
+{
+    return nonClientMetrics(ncm, screen ? screen->logicalDpi().first : 0);
+}
+
+bool QWindowsContext::nonClientMetricsForWindow(NONCLIENTMETRICS *ncm, const QPlatformWindow *win)
+{
+    return nonClientMetricsForScreen(ncm, win ? win->screen() : nullptr);
+}
+
 static inline QWindowsInputContext *windowsInputContext()
 {
     return qobject_cast<QWindowsInputContext *>(QWindowsIntegration::instance()->inputContext());
@@ -870,6 +1000,7 @@ static inline bool isInputMessage(UINT m)
     case WM_IME_STARTCOMPOSITION:
     case WM_IME_ENDCOMPOSITION:
     case WM_IME_COMPOSITION:
+    case WM_INPUT:
     case WM_TOUCH:
     case WM_MOUSEHOVER:
     case WM_MOUSELEAVE:
@@ -957,7 +1088,9 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
 
     switch (et) {
     case QtWindows::GestureEvent:
-        return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateGestureEvent(platformWindow->window(), hwnd, et, msg, result);
+        if (!(d->m_systemInfo & QWindowsContext::SI_SupportsPointer))
+            return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateGestureEvent(platformWindow->window(), hwnd, et, msg, result);
+        break;
     case QtWindows::InputMethodOpenCandidateWindowEvent:
     case QtWindows::InputMethodCloseCandidateWindowEvent:
         // TODO: Release/regrab mouse if a popup has mouse grab.
@@ -974,7 +1107,7 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
     case QtWindows::UnknownEvent:
         return false;
     case QtWindows::AccessibleObjectFromWindowRequest:
-#ifndef QT_NO_ACCESSIBILITY
+#if QT_CONFIG(accessibility)
         return QWindowsUiaAccessibility::handleWmGetObject(hwnd, wParam, lParam, result);
 #else
         return false;
@@ -1083,18 +1216,25 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
     case QtWindows::ExposeEvent:
         return platformWindow->handleWmPaint(hwnd, message, wParam, lParam);
     case QtWindows::NonClientMouseEvent:
-        if (platformWindow->frameStrutEventsEnabled())
+        if (!(d->m_systemInfo & QWindowsContext::SI_SupportsPointer) && platformWindow->frameStrutEventsEnabled())
             return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateMouseEvent(platformWindow->window(), hwnd, et, msg, result);
         break;
+    case QtWindows::NonClientPointerEvent:
+        if ((d->m_systemInfo & QWindowsContext::SI_SupportsPointer) && platformWindow->frameStrutEventsEnabled())
+            return sessionManagerInteractionBlocked() || d->m_pointerHandler.translatePointerEvent(platformWindow->window(), hwnd, et, msg, result);
+        break;
     case QtWindows::EnterSizeMoveEvent:
         platformWindow->setFlag(QWindowsWindow::ResizeMoveActive);
         return true;
     case QtWindows::ExitSizeMoveEvent:
         platformWindow->clearFlag(QWindowsWindow::ResizeMoveActive);
         platformWindow->checkForScreenChanged();
+        handleExitSizeMove(platformWindow->window());
         return true;
     case QtWindows::ScrollEvent:
-        return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateScrollEvent(platformWindow->window(), hwnd, msg, result);
+        if (!(d->m_systemInfo & QWindowsContext::SI_SupportsPointer))
+            return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateScrollEvent(platformWindow->window(), hwnd, msg, result);
+        break;
     case QtWindows::MouseWheelEvent:
     case QtWindows::MouseEvent:
     case QtWindows::LeaveEvent:
@@ -1104,10 +1244,20 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
                 window = window->parent();
             if (!window)
                 return false;
-            return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateMouseEvent(window, hwnd, et, msg, result);
+            if (!(d->m_systemInfo & QWindowsContext::SI_SupportsPointer))
+                return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateMouseEvent(window, hwnd, et, msg, result);
+            else
+                return sessionManagerInteractionBlocked() || d->m_pointerHandler.translateMouseEvent(window, hwnd, et, msg, result);
         }
+        break;
     case QtWindows::TouchEvent:
-        return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateTouchEvent(platformWindow->window(), hwnd, et, msg, result);
+        if (!(d->m_systemInfo & QWindowsContext::SI_SupportsPointer))
+            return sessionManagerInteractionBlocked() || d->m_mouseHandler.translateTouchEvent(platformWindow->window(), hwnd, et, msg, result);
+        break;
+    case QtWindows::PointerEvent:
+        if (d->m_systemInfo & QWindowsContext::SI_SupportsPointer)
+            return sessionManagerInteractionBlocked() || d->m_pointerHandler.translatePointerEvent(platformWindow->window(), hwnd, et, msg, result);
+        break;
     case QtWindows::FocusInEvent: // see QWindowsWindow::requestActivateWindow().
     case QtWindows::FocusOutEvent:
         handleFocusEvent(et, platformWindow);
@@ -1150,6 +1300,7 @@ bool QWindowsContext::windowsProc(HWND hwnd, UINT message,
             }
         break;
     case QtWindows::MouseActivateWindowEvent:
+    case QtWindows::PointerActivateWindowEvent:
         if (platformWindow->window()->flags() & Qt::WindowDoesNotAcceptFocus) {
             *result = LRESULT(MA_NOACTIVATE);
             return true;
@@ -1294,6 +1445,37 @@ bool QWindowsContext::handleContextMenuEvent(QWindow *window, const MSG &msg)
 }
 #endif
 
+void QWindowsContext::handleExitSizeMove(QWindow *window)
+{
+    // Windows can be moved/resized by:
+    // 1) User moving a window by dragging the title bar: Causes a sequence
+    //    of WM_NCLBUTTONDOWN, WM_NCMOUSEMOVE but no WM_NCLBUTTONUP,
+    //    leaving the left mouse button 'pressed'
+    // 2) User choosing Resize/Move from System menu and using mouse/cursor keys:
+    //    No mouse events are received
+    // 3) Programmatically via QSizeGrip calling QPlatformWindow::startSystemResize/Move():
+    //    Mouse is left in pressed state after press on size grip (inside window),
+    //    no further mouse events are received
+    // For cases 1,3, intercept WM_EXITSIZEMOVE to sync the buttons.
+    const Qt::MouseButtons currentButtons = QWindowsMouseHandler::queryMouseButtons();
+    const Qt::MouseButtons appButtons = QGuiApplication::mouseButtons();
+    if (currentButtons == appButtons)
+        return;
+    const Qt::KeyboardModifiers keyboardModifiers = QWindowsKeyMapper::queryKeyboardModifiers();
+    const QPoint globalPos = QWindowsCursor::mousePosition();
+    const QPlatformWindow *platWin = window->handle();
+    const QPoint localPos = platWin->mapFromGlobal(globalPos);
+    const QEvent::Type type = platWin->geometry().contains(globalPos)
+        ? QEvent::MouseButtonRelease : QEvent::NonClientAreaMouseButtonRelease;
+    for (Qt::MouseButton button : {Qt::LeftButton, Qt::RightButton, Qt::MiddleButton}) {
+        if (appButtons.testFlag(button) && !currentButtons.testFlag(button)) {
+            QWindowSystemInterface::handleMouseEvent(window, localPos, globalPos,
+                                                     currentButtons, button, type,
+                                                     keyboardModifiers);
+        }
+    }
+}
+
 bool QWindowsContext::asyncExpose() const
 {
     return d->m_asyncExpose;
@@ -1306,7 +1488,8 @@ void QWindowsContext::setAsyncExpose(bool value)
 
 QTouchDevice *QWindowsContext::touchDevice() const
 {
-    return d->m_mouseHandler.touchDevice();
+    return (d->m_systemInfo & QWindowsContext::SI_SupportsPointer) ?
+        d->m_pointerHandler.touchDevice() : d->m_mouseHandler.touchDevice();
 }
 
 static DWORD readDwordRegistrySetting(const wchar_t *regKey, const wchar_t *subKey, DWORD defaultValue)
@@ -1399,7 +1582,7 @@ extern "C" LRESULT QT_WIN_CALLBACK qWindowsWndProc(HWND hwnd, UINT message, WPAR
             marginsFromRects(ncCalcSizeFrame, rectFromNcCalcSize(message, wParam, lParam, 0));
         if (margins.left() >= 0) {
             if (platformWindow) {
-                platformWindow->setFrameMargins(margins);
+                platformWindow->setFullFrameMargins(margins);
             } else {
                 const QSharedPointer<QWindowCreationContext> ctx = QWindowsContext::instance()->windowCreationContext();
                 if (!ctx.isNull())